John Warren Posted June 1 Share Posted June 1 Next up a pair of MC40s for a complete going over including new chassis parts. 8 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted June 4 Share Posted June 4 You have your work cut out. I look forward to the restoration. Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 11 Author Share Posted June 11 The MC40 chassis from the Korean supplier are really quite nice. I had the factory bottom covers chem-etched and painted. 7 Quote Link to comment Share on other sites More sharing options...
jwc Posted June 13 Share Posted June 13 Looking like new. Fine work Quote Link to comment Share on other sites More sharing options...
Schu Posted June 13 Share Posted June 13 LOVELY work JW... I still would love to hear that new amp you built. 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 18 Author Share Posted June 18 And here we are about halfway thru the restoration. 5 Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 19 Share Posted June 19 Looks like they're going to be beautiful. 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 23 Author Share Posted June 23 The amplifiers power supplies and rectification for both B+ and the bias supply are located on the capacitor frame. This assembly takes the bulk of the labor to rewire on this project. The board holds capacitors for the tube circuits on one side and the resistors on the other. The finished amp came out quite nice. 5 Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 23 Author Share Posted June 23 The customer provided tubes were worn but still able to provide a respectable 0.12% THD+N at 16.9VRMS out into an 8Ohm load @1kHz. 2 Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 23 Author Share Posted June 23 Call me old-fashioned but the OEM power cable should be replaced with a 3-C cable with Earth prong. Safety First! Green is Earth White is Neutral Black is Death 5 Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted June 23 Share Posted June 23 As always beautiful work and verification of performance afterwards…👍 miketn 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 25 Author Share Posted June 25 Now time to work on the second unit. It's a bit different than the first unit. I think it's an earlier production asset based on SN. This is what I salvaged from the OEM assembly. The power and output transformers, the capacitor frame, the phenolic circuit board and the tube sockets. The electrolytic multi-section caps will be replaced with CE Mfg equivalents. The transformers show the extent of the potting encapsulant poured into each. The output transformer is shown in the top and in the second photo. Note the band strap clamp protruding from the potting. 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted July 3 Author Share Posted July 3 Complete! 7 Quote Link to comment Share on other sites More sharing options...
jwc Posted July 3 Share Posted July 3 Amazing. Work of Art 1 Quote Link to comment Share on other sites More sharing options...
frt8dog Posted July 4 Share Posted July 4 Very nice work…attention to detail, awesome! Quote Link to comment Share on other sites More sharing options...
John Warren Posted July 4 Author Share Posted July 4 Excellent, thank you all for the nice comments. I have a pair of MC60s here and one power supply transformer isn't providing any output voltage on the filament tap suggesting either a broken lead, or an open secondary. I haven't gone into the transformer but it might be as simple as a cracked lead. It the leads are ok something a bit more drastic will be required. Quote Link to comment Share on other sites More sharing options...
Moderators Travis In Austin Posted July 4 Moderators Share Posted July 4 @John Warren Dr. Warren: I referred a guy in another forum to you. He inherited two MC30 and an MX110 from his uncle. He lives in Boston, his Uncle, and equipment are in Omaha, NE. He has to have them shipped to him, suggested he call you first to confirm buying the shipping boxes from McIntosh or Vintage Audio (always worked for me) and discuss what is typically involved. Sent him links. Travis Quote Link to comment Share on other sites More sharing options...
John Warren Posted July 5 Author Share Posted July 5 How exciting, thank you Travis for taking the time and effort! Quote Link to comment Share on other sites More sharing options...
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